2001 blazer no heat/blend door movement
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Joined: Mar 2022
Posts: 2
2001 blazer no heat/blend door movement
Yes have 2001 blazer here. Temp control *** moves from hot.to cold but always cold. No coolant concern. Recert door stays open as well like ac is stuck on in control head. Blend door will not switch completely always blows out vent. Move to floor will have a little and the recert door closes half way. I'm only guessing but I believe it's the control head . Any one run threw this or have any ideas? Thanks
BF Guru
Joined: Dec 2016
Posts: 5,610
From: Moscow, ID
Welcome to the forum.
There are lots of threads on dealing with the quirks of the HVAC system.
There are three main things to check on these:
The cause for #3 will be leaks in the under-hood vacuum lines that supply vacuum to the HVAC actuators and also the 4wd front axle engagement mechanism. Leaks at the actuators themselves or the under-dash hoses seem to be pretty rare. If you have a three button transfer case, the vacuum system also is connected to the transfer case.
These vacuum actuated doors of the HVAC system work with the blend-door which is electronically controlled. So it is possible that your problem is only with the vacuum hoses. However, a broken gear in the blend-door actuator is not an uncommon problem.
I have link in my sig file to a thread on checking the vacuum hoses. You might start there since it is so much easier to check and repair than getting to the blend door actuator. The blend-door actuator can be replaced by going through the glove-box opening but it is a tight fit and small hands are a plus!
You didn't say if you have the "computer climate control" or manual HVAC system. The former is the one where you pick a temperature the HVAC system will try to attain. The manual and computer controlled systems use different blend-door actuators. Keep that in mind if it turns out you need one.
There are lots of threads on dealing with the quirks of the HVAC system.
There are three main things to check on these:
- Is the heater core plugged?
- Is the blend-door not working?
- Are the actuators for the directing the air in the HVAC system working?
The cause for #3 will be leaks in the under-hood vacuum lines that supply vacuum to the HVAC actuators and also the 4wd front axle engagement mechanism. Leaks at the actuators themselves or the under-dash hoses seem to be pretty rare. If you have a three button transfer case, the vacuum system also is connected to the transfer case.
These vacuum actuated doors of the HVAC system work with the blend-door which is electronically controlled. So it is possible that your problem is only with the vacuum hoses. However, a broken gear in the blend-door actuator is not an uncommon problem.
I have link in my sig file to a thread on checking the vacuum hoses. You might start there since it is so much easier to check and repair than getting to the blend door actuator. The blend-door actuator can be replaced by going through the glove-box opening but it is a tight fit and small hands are a plus!
You didn't say if you have the "computer climate control" or manual HVAC system. The former is the one where you pick a temperature the HVAC system will try to attain. The manual and computer controlled systems use different blend-door actuators. Keep that in mind if it turns out you need one.
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